Custom 12v HDD and power Lights for PCs

The table is finally finished just the custom case lights to add.  Each PC has red and blue 12v  LED lights surrounding them in the case as shown in the picture below.

Case LED lights
The the idea is to connect the motherboard power and HDD LED cables to a custom Arduino, which will control the strip lights surrounding each PC.  This will allow me to program a number of settings into the Arduino which can be changed based on some switches.

Some settings that I have in mind are;
  • Red = Power , Blue = HDD
  • Red = Power , Blue = HDD (inverted)
  • Always on (full - showcase mode, dim - mood lighting)
    • This should be available with both PCs off...(subtly important point)
  • Off
  • Fading
Having it controlled by the Atmel MCU will allow new options to be added later.

Some issues;
  • I can only use the PC ATX power supplies if one of the PCs is on, so an additional power would be necessary for the Arduino to cover this mode
  • With 2 ATX power supplies and a third for the Arduino I want to use Opti-couplers to separate the different supplies
  • The standard case LEDs stil have to work with the Arduino off, or regardless of what the 12v lights are doing
After performing some de-risking I found that the LED power supply from the motherboard couldn't supply enough current to power both the opticoupler and the case LED...not sure this was due to the specific motherboard.... or my dodgy circuits... but decided to drive the LED and opti-coupler from the ATX power supply, switched by a transistor.

LED and Opti-coupler driver

After testing on a breadboard I added a second transistor to flip the logic which was reversed by the first transistor (the LEDs were inverted).

So the plan
  • A daughter board for each PC to control the case LEDs and drive the Arduino inputs through on opti-coupler
  • Arduino with secondary power supply to control 12v LED strips based on switches and HDD and Power LED inputs
I have 1 prototype board and have started on the second daughter board....

More to follow.

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